id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
|---|---|---|
12477028 | Vertical ionisation potentials of a number of crown ethers from charge transfer bands of their EDA complexes. | Vertical ionisation potentials (I(v)D) of a number of crown ethers, viz. dibenzo-30-crown-10 (Crown 1), benzo-15-crown-5 (Crown 2), dibenzo-24-crown-8 (Crown 3), dicyclohexano-24-crown-8 (Crown 4) and 4'-nitrobenzo-15-crown-5 (Crown 5) are being reported for the first time from a study of EDA interaction of these crown... |
12477026 | Surface-enhanced Raman spectroscopy study on the structure changes of 4-mercaptopyridine adsorbed on silver substrates and silver colloids. | Surface-enhanced Raman scattering (SERS) of 4-mercaptopyridine (4-mpy) adsorbed on HNO3 etched silver foil, chemically deposited silver films (silver mirror) and silver colloids were measured. The SERS study has revealed that 4-mpy was adsorbed onto the three kinds of silver surfaces by a sulfur-silver bond with the pl... |
12477024 | Preparation and study on the solid inclusion complex of ciprofloxacin with beta-cyclodextrin. | The interaction of ciprofloxacin with beta-cyclodextrin (betaCD) has been studied by several analytical techniques, including 1H-NMR (nuclear magnetic resonance),13C-NMR, fluorescence spectroscopy, infrared (IR) spectroscopy, thermal analysis, and scanning electron microscope. In this paper, solid inclusion complex of ... |
12475040 | Electrochemiluminescence in aqueous solution of a ruthenium(II) bipyridyl complex containing a crown ether moiety in the presence of metal ions. | Changes in electrochemiluminescence (ECL) properties of a ruthenium polyazine compound containing a crown-ether moiety have been investigated in aqueous buffered solution. The electrochemistry, photophysics and ECL of (bpy)2Ru(AZA-bpy)2+ [bpy = 2,2'-bipyridine; AZA-bpy = 4-(N-aza-18-crown-6-methyl-2,2'-bipyridine)] in ... |
12475036 | Development and evaluation of a nano-electrospray ionisation source for atmospheric pressure ion mobility spectrometry. | A nano-electrospray ionisation source has been designed and constructed for a high temperature ion mobility spectrometer. The drift cell was modified by replacement of the 63Ni atmospheric pressure chemical ionisation source with a tube lens/desolvation region and operated using commercial nano-electrospray capillaries... |
12472200 | Effect of dialysis on erythrocyte membrane of chronically hemodialyzed patients. | The present work examines the role of uremia and the effect of dialysis treatment on red blood cells (RBCs) membrane properties of hemodialysis patients. The results showed that, the uremic patients had a lower values of erythrocyte deformability than that of healthy control subject. The median osmotic fragility (MOF) ... |
12467488 | High initial activity but low storage stability observed for several preparations of subtilisin Carslberg suspended in organic solvents. | Colyophilization with methyl-beta-cyclodextrin activates subtilisin Carlsberg by more than 200-fold in organic solvents, though this is a short-lived effect. About 93% of the enzyme's high initial activity observed in THF (at 45 degrees C) decreases exponentially with a t(1/2) of 1.8 h, until it reaches a residual acti... |
12463374 | Capillary electrophoresis of cytochrome P-450 epoxygenase metabolites of arachidonic acid. 2. Resolution of stereoisomers. | Each of the four regioisomers of epoxyeicosatrienoic acids (EETs) is a candidate for being an endothelial-dependent hyperpolarizing factor (EDHF). One regioisomer, 14,15-EET, stereospecifically blocks cyclooxygenases from converting arachidonic acid to prostaglandins and stereospecifically binds to cellular receptors. ... |
12463373 | Capillary electrophoresis of cytochrome P-450 epoxygenase metabolites of arachidonic acid. 1. Resolution of regioisomers. | The essential fatty acid arachidonate is oxidized by cytochrome P-450 epoxygenases to four epoxyeicosatrienoic acids (EETs): 14,15-, 11,12-, 8,9-, and 5,6-EETs. Each of the four EET regioisomers and their hydrolysis products (DHETs) has multiple paracrine and autocrine functions and may also potently dilate blood vesse... |
12459583 | Guest-dependent spin crossover in a nanoporous molecular framework material. | The nanoporous metal-organic framework Fe2(azpy)4(NCS)4.(guest) (azpy is trans-4,4'-azopyridine) displays reversible uptake and release of guest molecules and contains electronic switching centers that are sensitive to the nature of the sorbed guests. The switching of this material arises from the presence of iron(II) ... |
12458958 | Chiral separation of amino acids by capillary electrophoresis with octyl-beta-thioglucopyranoside as chiral selector. | 1-S-Octyl-beta-D-thioglucopyranoside (OTG) was evaluated as a chiral selector for the separation of dansyl-amino acids by capillary electrophoresis. Enantiomeric separations of the amino acids can be accomplished by judiciously adjusting the pH of the solution and the concentration of OTG. Better separation can be achi... |
12458943 | Hydroxyfullerene as a novel coating for solid-phase microextraction fiber with sol-gel technology. | Hydroxyfullerene (fullerol) as a novel coating for solid-phase microextraction (SPME) fiber was first prepared by a sol-gel technology. The coating procedure involving sol solution composition and conditioning process was presented. A fullerene polysiloxane surface-bonded porous coating on the fused-silica fiber surfac... |
12458799 | Evolutionary dynamics and population control during in vitro selection and amplification with multiple targets. | Iterative cycles of in vitro selection and amplification allow rare functional nucleic acid molecules, aptamers, to be isolated from large sequence pools. Here we present an analysis of the progression of a selection experiment that simultaneously yielded two families of RNA aptamers against two disparate targets: the ... |
12458790 | Aminoacyl-tRNA synthetases: versatile players in the changing theater of translation. | Aminoacyl-tRNA synthetases attach amino acids to the 3' termini of cognate tRNAs to establish the specificity of protein synthesis. A recent Asilomar conference (California, January 13-18, 2002) discussed new research into the structure-function relationship of these crucial enzymes, as well as a multitude of novel fun... |
12457709 | Differential regulation of apolipoprotein A-I/ATP binding cassette transporter A1-mediated cholesterol and phospholipid release. | We compared apolipoprotein A-I (apoA-I)-mediated release of cellular cholesterol and phospholipid among several fibroblast cell lines. ApoA-I induced phospholipid release from WI-38, MRC-5, BALB/3T3, L929 and CHO-K1, but not from COS-7, while cholesterol was released only from WI-38, MRC-5 and BALB/3T3 without correlat... |
12456112 | Comparative study on the enantiomer separation of 1,1'-binaphthyl-2,2'diyl hydrogenphosphate and 1,1'-bi-2-naphthol by liquid chromatography and capillary electrophoresis using single and combined chiral selector systems. | The chiral recognition ability of single and dual selectors, that were used as additives, have been investigated by HPLC and CE. Native beta- and gamma-cyclodextrins, permethylated beta-cyclodextrin, hydroxypropyl-beta-cyclodextrin, cholic acid and taurodeoxycholic acid sodium salts were applied as chiral selectors, wh... |
12456102 | Separation of stereoisomers of several furan derivatives by capillary gas chromatography-mass spectrometry, supercritical fluid chromatography, and liquid chromatography using chiral stationary phases. | The direct separation of several stereoisomers (enantiomers and geometrical isomers) of furan derivatives, important intermediates for the synthesis of physiologically active natural products, was achieved using capillary gas chromatography/mass spectrometry with a per-O-methyl-beta-cyclodextrin, supercritical fluid ch... |
12455645 | Enantiomeric separation of methamphetamine and related analogs by capillary zone electrophoresis: intelligence study in routine methamphetamine seizures. | A method for simultaneous enantiomeric separation of ephedrine, pseudoephedrine, and methamphetamine (MA) in a single run by simple capillary zone electrophoresis (CZE) with beta-cyclodextrin as a chiral selector is described. The effects of the buffer pH, phosphate concentration, beta-cyclodextrin concentration, volta... |
12446904 | Fluorometric detection of enzyme activity with synthetic supramolecular pores. | The reversible blockage of synthetic pores formed by rigid-rod beta barrels, either by substrates or products, was used to sense a variety of enzymatic reactions in high-throughput format with "naked-eye" fluorescent detection. Improvement of sensor sensitivity beyond three orders of magnitude by straightforward intern... |
12444644 | Structure and thermodynamics of alpha-, beta-, and gamma-cyclodextrin dimers. Molecular dynamics studies of the solvent effect and free binding energies. | The alpha-, beta-, and gamma-cyclodextrin (CyDs) dimers were studied by molecular dynamics (MD) simulations in water as an explicit solvent. The relative stability of dimers and the involved molecular interactions were determined. Three possible starting orientations were considered for the dimers: head-to-head, head-t... |
12444638 | Noncovalent secondary interactions in Co(II)Salen complexes: O2 binding and catalytic activity in cyclohexene oxygenation. | The O2 affinity of Co(II)Salen complexes 1-4 and their reactivity in cyclohexene oxygenation reactions of Co(II)Salen complexes 1-4 are modulated by noncovalent interactions such as hydrogen bonding and steric hindrance using a functionalized diamino bridge. Higher O2 affinity is observed in the case of efficient hydro... |
12444626 | Quantitative evaluation of the chloride template effect in the formation of dicationic [1(4)]imidazoliophanes. | The formation of macrocycles containing two imidazolium rings such as 1.2X and 2.2X is anion-directed through hydrogen bonding. The template effect exerted by the chloride anion in the ring-closure reaction of the monocationic model intermediate 9+ to yield the [1(4)]imidazoliophane 2(2+) has been evaluated. This effec... |
12445274 | Imaging immune surveillance by T cells and NK cells. | As T cells and natural killer (NK) cells survey the surface of other cells, cognate receptors and ligands are commonly organized into distinct micrometer-scale domains at the intercellular contact, creating an immune or immunological synapse (IS). We aim to address the still unanswered questions of how this organizatio... |
12445566 | Development and in vitro evaluation of an enteric-coated multiparticulate drug delivery system for the administration of piroxicam to dogs. | The aim of the study was to develop enteric-coated pellets for the administration of piroxicam (a poorly water-soluble drug) to small animals in order to avoid local gastrointestinal irritation, one of the major side effects of nonsteroidal anti-inflammatory drugs after oral ingestion. Pellets were made by an extrusion... |
12445556 | A novel particle engineering technology to enhance dissolution of poorly water soluble drugs: spray-freezing into liquid. | A novel cryogenic spray-freezing into liquid (SFL) process was developed to produce microparticulate powders consisting of an active pharmaceutical ingredient (API) molecularly embedded within a pharmaceutical excipient matrix. In the SFL process, a feed solution containing the API was atomized beneath the surface of a... |
12449789 | [Characteristics of cyclodextrin production using cyclodextrin glucanotransferases of various groups of microorganisms]. | Cyclodextrin glucanotransferases (CGTases; EC 2.4.1.19) from newly isolated mesophilic, thermophilic, alkalophilic, and halophilic bacilli, as well as from thermoactinomycetes, have been purified to homogeneity, and some of their physicochemical and biochemical characteristics (cyclizing, disproportionating, and hydrol... |
12443099 | The role of water molecules in a resorcinarene capsule as probed by NMR diffusion measurements. | [structure: see text] NMR diffusion measurements were used to probe the role of water molecules in a resorcinarene capsule in a CDCl(3) solution. It was found that the water/resorcinarene ratio affects both the chemical shift and the diffusion coefficient of the water molecules. From the NMR diffusion measurements we c... |
12443075 | A facile synthesis of large extraannular-functionalized phenyl-ethynyl macrocycles containing m-terphenyl units. | [reaction: see text] Two large extraannular-functionalized phenyl-ethynyl macrocycles containing m-terphenyl units are described. The synthesis of the m-terphenyl building blocks is based on the transformation of pyrylium salts to arenes. |
12440926 | Assembling phenomena of calix[4]hydroquinone nanotube bundles by one-dimensional short hydrogen bonding and displaced pi-pi stacking. | Using the computer-aided molecular design approach, we recently reported the synthesis of calix[4]hydroquinone (CHQ) nanotube arrays self-assembled with infinitely long one-dimensional (1-D) short hydrogen bonds (H-bonds) and aromatic-aromatic interactions. Here, we assess various calculation methods employed for both ... |
12440912 | Designing macromolecules for therapeutic applications: polyester dendrimer-poly(ethylene oxide) "bow-tie" hybrids with tunable molecular weight and architecture. | The design and preparation of new polyester dendrimer, poly(ethylene oxide) hybrid systems for drug delivery and related therapeutic applications, are described. These systems consist of two covalently attached polyester dendrons, where one dendron provides multiple functional handles for the attachment of therapeutica... |
12440903 | The trapping of a spontaneously "flipped-out" base from double helical nucleic acids by host-guest complexation with beta-cyclodextrin: the intrinsic base-flipping rate constant for DNA and RNA. | Beta-cyclodextrin, which forms stable host-guest complexes with purine bases, induces the melting of RNA and DNA duplexes below their normal melting temperatures. Alpha-cyclodextrin, which does not form stable complexes, has no effect on either RNA or DNA. Gamma-cyclodextrin, which forms weaker complexes, has no effect... |
12440899 | Homochiral supramolecular polymerization of an "S"-shaped chiral monomer: translation of optical purity into molecular weight distribution. | An "S"-shaped chiral motif of a p-xylylene-bridged bis(cyclic dipeptide) (1), having four hydrogen-bonding amide functionalities, formed a homochiral supramolecular polymer in solution. X-ray crystallography of a slightly modified version of 1 for an enhanced crystallinity showed one-dimensional columnar assemblies via... |
12440882 | Individual water-soluble dendrimer-encapsulated silver nanodot fluorescence. | Easily observed on the single molecule level, highly fluorescent and photostable silver nanoclusters have been photochemically prepared within poly(amidoamine) dendrimer hosts in aqueous solutions. The dendrimer cage stabilizes and solubilizes the nanoclusters to yield highly stable, photoactivated single nanodots rang... |
12440855 | Effects of structure of polyamidoamine dendrimer on gene transfer efficiency of the dendrimer conjugate with alpha-cyclodextrin. | To improve gene transfer activity of a new nonviral vector, a polyamidoamine dendrimer (G2) conjugate with alpha-cyclodextrin (alpha-CDE conjugate (G2)), we prepared alpha-CDE conjugates with dendrimer having different generations (G3 and G4), and their gene transfer activities were compared with those of alpha-CDE con... |
12440851 | Self-assembled ternary complex of cationic dendrimer, cucurbituril, and DNA: noncovalent strategy in developing a gene delivery carrier. | A ternary complex of PPI-DAB dendrimer [(1,4-diaminobutane); Gen = N; dendri-poly(propyleneimine); -[NHC(=O)CH(2)NH(2)(+)(CH(2))(4)NH(3)(+)](z)()], DNA, and cucurbituril (CB) was evaluated as an example of a totally self-assembled gene delivery carrier. The complex was formed in a noncovalent way in which DNA interacts... |
12440993 | Group I introns and RNA folding. | Before the discovery of catalytic RNA, tRNA molecules were the most studied RNA molecules for understanding RNA folding. Afterwards, group I introns, because of their stability and the fact that structural folding could be monitored by following their catalytic activity, became the molecule of choice for studying RNA a... |
12441796 | Virion-associated cholesterol is critical for the maintenance of HIV-1 structure and infectivity. | <h4>Objective</h4>HIV-1 particles are enriched with cholesterol; however, the significance of this cholesterol enrichment is unknown. This study examines the structural and functional roles of cholesterol in HIV-1 replication.<h4>Methods</h4>Using methyl-beta-cyclodextrin (CD) to remove cholesterol from the HIV-1 envel... |
12438453 | Guanosine nucleotides inhibit different syndromes of PTHrP excess caused by human cancers in vivo. | There are two well-described syndromes caused by tumor production of parathyroid hormone-related peptide (PTHrP), namely osteolytic bone disease associated with breast cancer and humoral hypercalcemia of malignancy (HHM) that occurs with or without bone metastasis. Both syndromes have been shown experimentally to be in... |
12438250 | Convection-enhanced delivery of boronated epidermal growth factor for molecular targeting of EGF receptor-positive gliomas. | Convection enhanced delivery (CED) is potentially a powerful method to improvethe targeting of macromolecules to the central nervous system by applying a pressure gradient to establish bulk flow through the brain interstitium during infusion. The purpose of the present study was to evaluate CED as a means to improve th... |
12439721 | Carcinoma-like vascular density in atypic keratoacanthoma suggests malignant progression. | Differential diagnosis between keratoacanthomas and well differentiated squamous cell carcinomas based on clinical and histomorphological data is problematic. Recent findings of cellular atypia in a large proportion of keratoacanthomas indicated that these potentially 'self-healing' cutaneous neoplasms had the potentia... |
12437348 | Conformational changes in nitric oxide synthases induced by chlorzoxazone and nitroindazoles: crystallographic and computational analyses of inhibitor potency. | Nitric oxide is a key signaling molecule in many biological processes, making regulation of nitric oxide levels highly desirable for human medicine and for advancing our understanding of basic physiology. Designing inhibitors to specifically target one of the three nitric oxide synthase (NOS) isozymes that form nitric ... |
12437322 | High-symmetry coordination cages via self-assembly. | We provide a summary of our results in three-dimensional, coordination-driven self-assembly based on the directional-bonding methodology, in which the stoichiometric mixing of complementary building blocks, with appropriate, predefined geometries, leads to targeted, nanoscopic cages. Using this motif, we have synthesiz... |
12437319 | Classic annulenes, nonclassical applications. | This Account details the application of [n]annulenes as functional building blocks for electromechanical actuators, double-helical ladder polymers, and protecting groups for supramolecular interactions. Specifically, redox-induced conformational changes occurring in [8]annulenes are utilized as the transducing element ... |
12437318 | Replacing the nucleobases in DNA with designer molecules. | DNA is not only a carrier of genetic information, but it is also a versatile supramolecular scaffold, arranging smaller organic structures into predesigned geometries. Herein are discussed molecular strategies in which the natural DNA bases on the sugar-phosphate backbone are replaced by other molecules. Some of the ba... |
12433993 | Visualization of hemiknot DNA structure with an atomic force microscope. | The hemiknot, a novel type of DNA structure in which a loop is stabilized by threading one end of the duplex through another, has been studied in this paper. The hemiknot was obtained by reassociation of a DNA fragment with (CA/TG)n inserts of different lengths. Slow and fast migrating products were purified by gel ele... |
12433489 | Bacillus macerans cyclomaltodextrin glucanotransferase transglycosylation reactions with different molar ratios of D-glucose and cyclomaltohexaose. | It was found that Bacillus macerans cyclomaltodextrin glucanotransferase (CGTase) reacts with cyclomaltohexaose (alpha-cyclodextrin, alpha-CD) to give a series of cyclomaltooligosaccharides (cyclomaltodextrins, CDs), having seven to more than 20 D-glucose residues and maltooligosaccharides (maltodextrins, MDs) from G5 ... |
12433086 | Dependence of ion selectivity on ordered orientation of neutral carriers in ion-sensing membranes based on thermotropic liquid crystals. | Thermotropic liquid-crystalline compounds were applied as membrane materials (membrane solvent and neutral carrier) for neutral carrier-type ion sensors to investigate how the ordered arrangement of neutral carriers affects the property of the resulting ion sensors. Nematic, smectic, and cholesteric liquid-crystalline ... |
12431106 | Supramolecular polymer chemistry: self-assembling dendrimers using the DDA.AAD (GC-like) hydrogen bonding motif. | Heterocyclic unit 2 containing complementary donor-donor-acceptor (DDA) and acceptor-acceptor-donor (AAD) hydrogen bonding arrays at an angle of about 60 degrees was designed to self-assemble into a hexamer. To investigate whether this unit could self-assemble dendrimers, the 2,8-diamino-2-N-ethylpyrimido-(4,5-b)(1,8)n... |
12431093 | The bicyclic n,n'-diacylaminal: a new motif for molecular self-assembly. | A cage-shaped N,N'-diacylaminal crystallizes from some aromatic solvents as "supramolecular chair cyclohexanes", squat cylindrical hexamers with approximate D3d symmetry containing two arene molecules, and from other aromatic and nonaromatic solvents as infinite tapes. A homologous diacylaminal crystallizes only as an ... |
12431074 | The practical synthesis of a novel and highly potent analogue of bryostatin. | Macrocycle 1 is a new highly potent analogue of bryostatin 1, a promising anti-cancer agent currently in human clinical trials. In vitro, 1 displays picomolar affinity for PKC and exhibits over 100-fold greater potency than bryostatin 1 when tested against various human cancer cell lines. Macrocycle 1 can be generated ... |
12415110 | Quantifying signaling-induced reorientation of T cell receptors during immunological synapse formation. | Productive T cell recognition of antigen-presenting cells (APCs) is normally accompanied by the formation of a cell-cell contact called the "immunological synapse." Our understanding of the steps leading up to this formation has been limited by the absence of tools for analyzing 3D surfaces and surface distributions as... |
12429455 | Acetazolamide: future perspective in topical glaucoma therapeutics. | Through this review it is contemplated that acetazolamide (ACZ), an age-old treatment for glaucoma with a myriad of side effects and inadequate topical effectiveness, may be formulated into a topically effective agent by utilizing various newer formulation approaches of ocular drug delivery. Even though it has a poor s... |
12427822 | Properties of unitary granule cell-->Purkinje cell synapses in adult rat cerebellar slices. | The cerebellar cortex contains huge numbers of synapses between granule cells and Purkinje cells. These synapses are thought to be a major storage site for information required to execute coordinated movements. To obtain a quantitative description of this connection, we recorded unitary synaptic responses between granu... |
12427018 | Molecular recognition of oligosaccharide epitopes by a monoclonal Fab specific for Shigella flexneri Y lipopolysaccharide: X-ray structures and thermodynamics. | The antigenic recognition of Shigella flexneri O-polysaccharide, which consists of a repeating unit ABCD [-->2)-alpha-L-Rhap-(1-->2)-alpha-L-Rhap-(1-->3)-alpha-L-Rhap-(1-->3)-beta-D-GlcpNAc-(1-->], by the monoclonal antibody SYA/J6 (IgG3, kappa) has been investigated by crystallographic analysis of the Fab domain and i... |
12427015 | Characterization of the role of the N-loop of MIP-1 beta in CCR5 binding. | MIP-1beta is a CC-chemokine that plays a role in inflammation and host defense mechanisms by interacting with its specific receptor CCR5. CCR5 is a major coreceptor for macrophage-tropic human immunodeficiency virus (HIV), and as a consequence, MIP-1beta can inhibit HIV entry. It is therefore of interest to understand ... |
12425617 | Self-assembly of nanoscale, porous T-symmetric molecular adamantanoids. | Treatments of lanthanide nitrate or perchlorate and C2-symmetric 2,2'-hydroxy-1,1'-binaphthalene-6,6'-dicarboxylic acid (6,6'-H2BDA) led to diastereoselective self-assembly of nanoscale, porous molecular adamantanoids [Ln4(BDA)6(H2O)12]*12DMF (Ln = Gd, La, 1a,b). These adamantanoid clusters possess perfect T symmetry a... |
12425613 | "ortho-Wurster's crowns": synthesis and properties of a novel phenylenediamine-based redox-active macrocyclic ligand. | A hybrid, macrocyclic structure based on o-phenylenediamine and a crown ether promotes an intimate mutual interaction with a bound potassium ion in the form of chelation by the redox-active moiety. A general synthetic method and properties are described for the first member of a new class of redox-active, lariat-type m... |
12426386 | From chloroplasts to photosystems: in situ scanning force microscopy on intact thylakoid membranes. | Envelope-free chloroplasts were imaged in situ by contact and tapping mode scanning force microscopy at a lateral resolution of 3-5 nm and vertical resolution of approximately 0.3 nm. The images of the intact thylakoids revealed detailed structural features of their surface, including individual protein complexes over ... |
12426379 | Clathrin light and heavy chain interface: alpha-helix binding superhelix loops via critical tryptophans. | Clathrin light chain subunits (LCa and LCb) contribute to regulation of coated vesicle formation to sort proteins during receptor-mediated endocytosis and organelle biogenesis. LC binding to clathrin heavy chain (HC) was characterized by genetic and structural approaches. The core interactions were mapped to HC residue... |
12425675 | Enzyme-based molecular imprinting with metals. | Aromatic monomers with various functional groups were utilized in horseradish peroxidase-catalyzed polymerization reactions with metal ions Cu(II), Ni(II), and Fe(III) as imprinting templates. The approach described combines molecular imprinting with enzymatic free radical coupling. Selectivity in metal ion affinity be... |
12425652 | Supramolecular formation of antibodies with viologen dimers: utilization for amplification of methyl viologen detection signals in surface plasmon resonance sensor. | Monoclonal antibodies for 1-(carboxypentyl)-1'-methyl-4,4'-bipyridinium dichloride have been prepared. The complex formation of one of the antibodies, 10D5, with viologen dimer has been studied by a biosensor technique based on surface plasmon resonance. The dissociation constants of the complex between antibody 10D5 a... |
12425651 | Stepwise self-assembled poly(amidoamine) dendrimer and poly(styrenesulfonate) microcapsules as sustained delivery vehicles. | Hollow microcapsules comprised of poly(styrenesulfonate) (PSS) and a fourth generation poly(amidoamine) dendrimer (4G PAMAM) were prepared by depositing PSS/4G PAMAM multilayers on melamine formaldehyde (MF) colloid particles by the layer-by-layer self-assembly technique and subsequently dissolving the templated cores.... |
12424373 | Macromolecular architecture in eukaryotic cells visualized by cryoelectron tomography. | Electron tomography of vitrified cells is a noninvasive three-dimensional imaging technique that opens up new vistas for exploring the supramolecular organization of the cytoplasm. We applied this technique to Dictyostelium cells, focusing on the actin cytoskeleton. In actin networks reconstructed without prior removal... |
12423069 | A chiral A2 B2 macrocyclic minireceptor with extreme enantioselectivity. | We describe a novel macrocyclic minireceptor that is assembled from a chiral 1,2-diamine and 5-allyloxyisophthalic acid. After immobilization on HPLC silica, the chiral macrocycle preferentially binds the L-enantiomers of simple amino acid derivatives, with enantioselectivities values up to 3.0 kcal/mol. [structure: se... |
12423168 | Functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines via stille-type cross-coupling procedures. | Stille-type cross-coupling procedures are utilized in order to prepare a variety of functionalized 2,2'-bipyridines and 2,2':6',2' '-terpyridines. Such N-heterocyclic compounds are of great interest as chelating ligands for transition-metal ions in the field of supramolecular chemistry. Various mono- and disubstitued 2... |
12423149 | Chemical synthesis of cyclodextrins by using intramolecular glycosylation. | An efficient synthesis of cyclodextrins (CDs) by using the intramolecular glycosylation is demonstrated. alpha-CD, an alpha(1-->4)linked hexaglucoside, was prepared via a block condensation of three maltose units. A modified key maltose intermediate as a precursor to both glycosyl donor and acceptor components was prep... |
12423124 | Probing polyvalency in artificial systems exhibiting molecular recognition. | An approach to the study of polyvalency-the interaction of polyvalent receptors with polyvalent ligands-in unnatural systems is outlined. In this study, the complexation of dibenzylammonium cations by dibenzo[24]crown-8 or benzometaphenylene[25]crown-8 is utilized as the component receptor-ligand interaction. Two analo... |
12424126 | A motif of a microbial starch-binding domain found in human genethonin. | The sequence of the starch-binding domain present in 10% of amylolytic enzymes of microbial origin and classified as the carbohydrate-binding module family 20, was identified in the equivalent part of sequence of human genethonin, a skeletal muscle protein of unknown function. The sequence identity between the starch-b... |
12423638 | Oxyphor R2 and G2: phosphors for measuring oxygen by oxygen-dependent quenching of phosphorescence. | Oxygen-dependent quenching of phosphorescence is a useful and essentially noninvasive optical method for measuring oxygen in vivo and in vitro. Calibration of the phosphors is absolute, and once phosphors have been calibrated in one laboratory the same constants can be used by anyone else as long as the measurement is ... |
12418913 | Self-assembled M(6)L(4)-type coordination nanocage with 2,2'-bipyridine ancillary ligands. Facile crystallization and X-ray analysis of shape-selective enclathration of neutral guests in the cage. | Hollow and roughly spherical cage 1 (ca. 2 nm in diameter) is self-assembled from 2,4,6-tri(4-pyridyl)-1,3,5-triazine (2) and Pd(diamine)(ONO(2))(2) (3). This cage compound enclathrates a variety of neutral organic molecules in an aqueous phase. Unlike cage 1a, which possesses ancillary ethylenediamine ligands on the m... |
12418902 | From chiral counterions to twisted membranes. | In membranes, the chirality of the amphiphile constituents is sometimes expressed at a supramolecular scale of nanometers or micrometers. We have recently reported that membranes of nonchiral dicationic n-2-n amphiphiles can also be chirally twisted upon interacting with chiral tartrate counterions. Here, we demonstrat... |
12418900 | Quinoxaline-bridged porphyrinoids. | Quinoxaline-bridged porphyrinoids (3), the first macrocycles containing dipyrrolylquinoxaline (DPQ, 1) subunits, were synthesized from the condensation of the diformyl-substituted DPQ derivatives (2) and 1,8-diaminoanthracene. The resulting structures were confirmed by X-ray analyses, which showed encapsulation of CHCl... |
12418897 | Chemosensors for the marine toxin saxitoxin. | Eleven anthracylmethyl crown ethers have been synthesized and evaluated as fluorescence sensors for the marine toxin saxitoxin. Fluorescence enhancement data are consistent with a 1:1 binding complex for all crowns. The binding constants are in the range of 10(4) M(-)(1) in ammonium phosphate buffer (pH 7.1) in 80% eth... |
12418878 | Cooperative host/guest interactions via counterion assisted chelation: pseudorotaxanes from supramolecular cryptands. | Addition of di- or tritopic hydrogen bond accepting anions to solutions of bis(5-hydroxymethyl-1,3-phenylene)-32-crown-10 and paraquat di(hexafluorophosphate) serves to enhance host/guest interaction. In particular, addition of Et4N+CF3COO- effectively boosts Ka 14-fold, as estimated by 1H NMR studies. Similar increase... |
12418868 | Controlled fabrication of cross-linked nanoparticles/polymer composite thin films through the combined use of surface-initiated atom transfer radical polymerization and gas/solid reaction. | A promising strategy for the controlled synthesis of inorganic/polymeric nanocomposites may be sustained by fabricating cross-linked PbS nanoparticles/polymer composite thin films through combining surface-initiated atom transfer radical polymerization (ATRP) and gas/solid reaction. The introduction of Pb ions through ... |
12418862 | Macrocyclic aromatic ether-imide-sulfones: versatile supramolecular receptors with extreme thermochemical and oxidative stability. | Macrocyclic receptors having extreme thermo-oxidative stability, and which bind a wide range of electron-donor substrates via pi-stacking donor-acceptor interactions, are accessible by cycloimidization of an amine-functionalized aryl ether-sulfone with pyromellitic dianhydride or 1,4,5,8-naphthalenetetracarboxylic dian... |
12419244 | Bid, Bax, and lipids cooperate to form supramolecular openings in the outer mitochondrial membrane. | Bcl-2 family proteins regulate the release of proteins like cytochrome c from mitochondria during apoptosis. We used cell-free systems and ultimately a vesicular reconstitution from defined molecules to show that outer membrane permeabilization by Bcl-2 family proteins requires neither the mitochondrial matrix, the inn... |
12417689 | Evidence that 5-HT2A receptors in the hypothalamic paraventricular nucleus mediate neuroendocrine responses to (-)DOI. | The present study determined whether the serotonin2A (5-HT2A) receptors in the hypothalamic paraventricular nucleus mediate the neuroendocrine responses to a peripheral injection of the 5-HT2A/2C receptor agonist (-)DOI [(-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane]. The 5-HT2A receptor antagonist MDL100,907 ((+/-)... |
12417684 | Dopamine D3 receptor antagonism inhibits cocaine-seeking and cocaine-enhanced brain reward in rats. | dopamine D3 receptor is preferentially localized to the mesocorticolimbic dopaminergic system and has been hypothesized to play a role in cocaine addiction. To study the involvement of the D3 receptor in brain mechanisms and behaviors commonly assumed to be involved in the addicting properties of cocaine, the potent an... |
12417032 | Chaperone-like functions of high-mannose type and complex-type N-glycans and their molecular basis. | It has recently become apparent that high-mannose type N-glycans directly promote protein folding, whereas complex-type ones play a crucial role in the stabilization of protein functional conformations through hydrophobic interactions with the hydrophobic protein surfaces. Here an attempt was made to understand more de... |
12241528 | Cytoplasmic interactions of syndecan-4 orchestrate adhesion receptor and growth factor receptor signalling. | Syndecan-4 is a ubiquitous transmembrane proteoglycan that localizes to the focal adhesions of adherent cells and binds to a range of extracellular ligands, including growth factors and extracellular-matrix proteins. Engagement of syndecan-4 is essential for adhesion formation in cells adhering via certain integrins, a... |
12137566 | Mitochondrial aspartate aminotransferase catalyses cysteine S-conjugate beta-lyase reactions. | Rat liver mitochondrial aspartate aminotransferase (a homodimer) was shown to catalyse a beta-lyase reaction with three nephrotoxic halogenated cysteine S-conjugates [ S -(1,1,2,2-tetrafluoroethyl)-L-cysteine, S -(1,2-dichlorovinyl)-L-cysteine and S -(2-chloro-1,1,2-trifluoroethyl)-L-cysteine], and less effectively so ... |
12413691 | High affinity binding of long-chain polysialic acid to antibody, and modulation by divalent cations and polyamines. | Long-chain polysialic acid (PSA) is expressed on the vertebrate neural cell adhesion molecule (NCAM) during neuronal plasticity. Its structural similarity to the capsular PSAs of some pathogenic bacteria has hampered the development of polysaccharide vaccines against meningitis. The antibodies formed during immunizatio... |
12414714 | Excluded volume effect within the continuous model for the fluorescence energy transfer. | We consider and discuss the transfer of electronic energy between donor and acceptor molecules, both continuously distributed in an infinite space. In particular, the ensemble-average fluorescence intensity decay for the donor was calculated, taking into account the excluded volume. The latter may be associated either ... |
12414707 | The structure of Ca(2+) release units in arthropod body muscle indicates an indirect mechanism for excitation-contraction coupling. | The relative disposition of ryanodine receptors (RyRs) and L-type Ca(2+) channels was examined in body muscles from three arthropods. In all muscles the disposition of ryanodine receptors in the junctional gap between apposed SR and T tubule elements is highly ordered. By contrast, the junctional membrane of the T tubu... |
12414697 | Lipid intermediates in membrane fusion: formation, structure, and decay of hemifusion diaphragm. | Lipid bilayer fusion is thought to involve formation of a local hemifusion connection, referred to as a fusion stalk. The subsequent fusion stages leading to the opening of a fusion pore remain unknown. The earliest fusion pore could represent a bilayer connection between the membranes and could be formed directly from... |
12414676 | Analysis and evaluation of channel models: simulations of alamethicin. | Alamethicin is an antimicrobial peptide that forms stable channels with well-defined conductance levels. We have used extended molecular dynamics simulations of alamethicin bundles consisting of 4, 5, 6, 7, and 8 helices in a palmitoyl-oleolyl-phosphatidylcholine bilayer to evaluate and analyze channel models and to li... |
12414518 | Tau assembly in inducible transfectants expressing wild-type or FTDP-17 tau. | Conditional expression systems for 4-repeat wild-type (WT) tau or the corresponding mutants V337M and R406W were established in human neuroglioma H4 cells to study the effect of tau mutations on the physicochemical properties of tau, and to develop a cellular model for the formation of filamentous tau characteristic of... |
12410834 | Molecular and functional analysis of the type III secretion signal of the Salmonella enterica InvJ protein. | Central to the pathogenicity of Salmonella enterica is the function of a type III secretion system (TTSS) encoded within a pathogenicity island at centisome 63 (SPI-1). An essential component of this system is a supramolecular structure termed the needle complex. Proteins to be delivered into host cells possess specifi... |
12411499 | The phage N4 virion RNA polymerase catalytic domain is related to single-subunit RNA polymerases. | In vitro, bacteriophage N4 virion RNA polymerase (vRNAP) recognizes in vivo sites of transcription initiation on single-stranded templates. N4 vRNAP promoters are comprised of a hairpin structure and conserved sequences. Here, we show that vRNAP consists of a single 3500 amino acid polypeptide, and we define and charac... |
12411477 | Molecular architecture and mechanism of an icosahedral pyruvate dehydrogenase complex: a multifunctional catalytic machine. | Electron cryo-microscopy of 'single particles' is a powerful method to determine the three-dimensional (3D) architectures of complex cellular assemblies. The pyruvate dehydrogenase multi-enzyme complex couples the activity of three component enzymes (E1, E2 and E3) in the oxidative decarboxylation of pyruvate to genera... |
12408908 | Comparative studies of the influence of cyclodextrins on the stability of the sunscreen agent, 2-ethylhexyl-p-methoxycinnamate. | The effects of beta-cyclodextrin (beta-CD) and hydroxypropyl-beta-cyclodextrin (HP-beta-CD) on the base-catalyzed degradation and light-induced decomposition of the sunscreen agent, trans-2-ethylhexyl-p-methoxycinnamate (trans-EHMC) were investigated. Reversed-phase liquid chromatography was used to study the interacti... |
12408907 | Assessment of solid-state interactions of naproxen with amorphous cyclodextrin derivatives by DSC. | A microcalorimetric method based on differential scanning calorimetry (DSC) of drug-additive binary systems to assess kneading-induced interactions was applied to naproxen (NAP) in combinations with amorphous hydroxypropyl beta-cyclodextrin (HPbetaCd), beta-cyclodextrin sulfobutyl ether, sodium salt ((SBE)(7m)-betaCd),... |
12408894 | Determination of ketoprofen enantiomers in human serum by capillary zone electrophoresis: man pharmacokinetic studies after administration of rac-ketoprofen tablets. | A rapid and stereospecific capillary zone electrophoresis (CZE) method to quantify ketoprofen (KTP) enantiomers was developed. The KTP enantiomers and (+)-S-naproxen [(+)-S-NPX] as an internal standard (IS) were extracted with methylene chloride from serum acidified. Recovery of both enantiomers was in the range of 85-... |
12409996 | The selective glycine antagonist gavestinel lacks phencyclidine-like behavioral effects. | Gavestinel [GV150526A; ( E)-3[(phenylcarbamoil)ethenyl]-4,6-dichloroindole-2-carboxylic acid sodium salt] is a selective antagonist at the strychnine-insensitive glycine site of the -methyl-D-aspartate (NMDA) receptor. It was tested for its ability to substitute for phencyclidine (PCP) in rats and rhesus monkeys traine... |
12406684 | High-level expression and characterization of a secreted recombinant cation-dependent mannose 6-phosphate receptor in Pichia pastoris. | Mannose 6-phosphate receptors (MPRs) form essential components of the lysosomal enzyme targeting system by binding newly synthesized acid hydrolases with high (nM) affinity. We report the use of Pichia pastoris as a host to efficiently express the extracytoplasmic ligand-binding domain of the cation-dependent mannose 6... |
12406682 | Purification and characterization of progenipoietins produced in Escherichia. coli. | The progenipoietins (ProGPs) are a family of genetically engineered chimeric proteins that contain receptor agonist activity for both fetal liver tyrosine kinase-3 and the granulocyte colony-stimulating factor receptor. These unique proteins have previously been shown to induce the proliferation of multiple cell lineag... |
12405853 | X-ray absorption and resonance Raman studies of methyl-coenzyme M reductase indicating that ligand exchange and macrocycle reduction accompany reductive activation. | Methyl-coenzyme M reductase (MCR) catalyzes methane formation from methyl-coenzyme M (methyl-SCoM) and N-7-mercaptoheptanoylthreonine phosphate (CoBSH). MCR contains a nickel hydrocorphin cofactor at its active site, called cofactor F(430). Here we present evidence that the macrocyclic ligand participates in the redox ... |
12405847 | Remarkably stable iron porphyrins bearing nonheteroatom-stabilized carbene or (alkoxycarbonyl)carbenes: isolation, X-ray crystal structures, and carbon atom transfer reactions with hydrocarbons. | Reactions of [Fe(TPFPP)] (TPFPP = meso-tetrakis(pentafluorophenyl)porphyrinato dianion) with diazo compounds N(2)C(Ph)R (R = Ph, CO(2)Et, CO(2)CH(2)CH=CH(2)) afforded [Fe(TPFPP)(C(Ph)R)] (R = Ph (1), CO(2)Et (2), CO(2)CH(2)CH=CH(2) (3)) in 65-70% yields. Treatment of 1 with N-methylimidazole (MeIm) gave the adduct [Fe(... |
12405812 | The first chiral organometallic triangle for asymmetric catalysis. | A family of chiral organometallic triangles based on cis-Pt(PEt3)2 metallocorners and enantiopure atropisomeric bis(alkynyl) bridging ligands (L1-4) has been synthesized and characterized by 1H, 13C{1H}, and 31P{1H} NMR, UV-vis, and circular dichroism (CD) spectroscopies, FAB and MALDI-TOF mass spectrometry, and microa... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.